To find the average rate of change of annual sales, we use the formula for the average rate of change between two points:

$\text{Average rate of change} = \frac{\text{Change in sales}}{\text{Change in time}}$

Part (a): Average Rate of Change Between 2002 and 2003

• Sales in 2002: 441 million dollars
• Sales in 2003: 447 million dollars

Change in sales:

$447 - 441 = 6 \text{ million dollars}$

Change in time:

$2003 - 2002 = 1 \text{ year}$

Average rate of change:

$\frac{6 \text{ million dollars}}{1 \text{ year}} = 6 \text{ million dollars/year}$

So, the average rate of change of annual sales between 2002 and 2003 is 6 million dollars/year.

Part (b): Average Rate of Change Between 2002 and 2004

• Sales in 2002: 441 million dollars
• Sales in 2004: 441 million dollars

Change in sales:

$441 - 441 = 0 \text{ million dollars}$

Change in time:

$2004 - 2002 = 2 \text{ years}$

Average rate of change:

$\frac{0 \text{ million dollars}}{2 \text{ years}} = 0 \text{ million dollars/year}$

So, the average rate of change of annual sales between 2002 and 2004 is 0 million dollars/year.

Would you like any more details or have any other questions?

Here are some related questions you might find interesting:

1. What is the total change in sales from 1998 to 2006?
2. How do you interpret the negative rate of change in sales after 2003?
3. What is the overall trend in sales from 1998 to 2006?
4. How would you model this sales data with a polynomial function?
5. What is the maximum sales value, and in what year does it occur?

Tip: The average rate of change is a useful way to understand how a quantity is changing over time, similar to the concept of slope in algebra.